The authors present the results of an investigation of the rate of electron-electron scattering in the two-dimensional electron gas of the Si inversion layer. The electron-electron scattering rate was extracted by analysis of the negative magnetoresistance in the regime of weak localisation when kFl>1, where kF is the Fermi wavevector and l is the mean free path for elastic scattering. The results showed that over a wide range of kFl, carrier concentration and electron mobility the scattering rate was given by two processes which were additive. The first was the normal T2 (Landau-Baber) law and the second was the T law expected when the effects of disorder are considered. There was no evidence for the recently proposed T ln T law.